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RALPH N. BAKERGeneral Electric Company-Space Division
Beltsville, MD 20705
LANDSAT Data: A NewPerspective for GeologyA review of the utilization of LANDSAT imagery for geologicalinterpretation.
T HE LANDSAT (formerly ERTS) satelliteprogram has been in existence for just
over two years, and in this brief time hasadded a whole new dimension to the study ofour Earth. Scientists from all over the worldhave used data measured by LANDSAT'ssensors (telemetered down from a580-mile-high vantage point in space) tomonitor pollution and crop growth, explorefor minerals and petroleum, and conduct ahost of other investigations ranging from
geologic mapping, mineral and petroleumexploration, and natural hazards surveys. Thecategories are arbitrary, and results of investigations might fit equally well into morethan one of these.
REGIONAL STRUCTURAL STUDIES
Several investigators studied regionalstructures and their relationships in LANDSAT imagery, availing themselves of a perspective previously impossible to achieve.
ABSTRACT: The LANDSAT (formerly ERTS) program, while conceived and implemented as a research and development project, hasbeen used as an operational orbital remote sensing system providingdata of considerable value to various branches of geology. Areas inwhich the satellite imagery has been found most useful include regional interpretations ofgeologic structure,lupdating and verifying ofgeologic maps, mineral and petroleum exploration, and the monitoring of natural hazards such as large-scale erosion and seismicity.Investigations in these areas of application demonstrate the widevariety of uses presently undertaken or envisioned for the future.Many benefits have already been felt; others will be seen in the nearfuture where the promise ofmineral or petroleum concentration willbe realized through conventional ground based and satellite exploration techniques. LANDSAT will aid considerably in pinpointing thelikely site; "hands on" geology will do the rest.
animal migration patterns to iceberg monitoring. The mission, originally designed for research and development, has for all practicalpurposes been considered "operational"from the user's point of view.
To geologists, the regional overview andrepetitive coverage of LANDSAT data hasbeen particularly useful, enabling them totake advantage of vegetation and sun anglechanges in their attempts to unravel the physical history and setting of the Earth. Successful LANDSAT investigations in geology canbe grouped for convenience into four generalcategories: regional structural studies,
Y. Isachsen of New York State's GeologicalSurvey used the IOO-by-IOO-mile images toconstruct a mosaic of the State and neighboring regions. This mosaic shows, at aglance, geologic relationships of New YorkState's diverse terrain, major rock units, glacial features, large scale lineaments, and circular structures (Figure I). Isachsen wentinto the field to verify the existence of manyof these features discovered in the LANDSAT mosaic, and demonstrated how onecould use satellite imagery to discern features unsuspected at a larger scale.
Houston and Marrs, LANDSAT inves-
PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING,
Vol. 41, No. 10, October 1975, pp. 1233-1239.1233
1234 PHOTOGRAMMETRIC E GINEERING & REMOTE SENSING, 1975
FIG. 1. LANDSAT mosaic and lineament map of eastern New York State (after Isachsen, 1973).
tigators from the University of Wyoming,studied geologic structures in Wyoming byusing a LANDSAT mosaic, and reported thattheir interpretations compared favorablywith known ground truth of the region. Whilethis region had been reasonably well mappedby conventional field surveys, theHouston-Marrs study points out the possibility of interpreting poorly mapped regionswith a minimum of ground truth, time, andcost with some measure of confidence.
In the East where climate is generally lessarid than in some Western States, LANDSATinvestigators have still been able to collectvaluable geologic information despite theheavier vegetation cover. For example, regional lineaments were discovered and mapped by Gold and co-investigators at PennState, using LANDSAT imagery of thethickly forested Pennsylvania Appalachians.A private consulting firm has appliedcomputer-aided enhancement techniques (inthis case General Electric Company'sIMAGE 100 multispectral image processingand display system) to imagery of other areasin eastern Pennsylvania, with success in distinguishing rock outcrops oflimited areal extent. Thus, while imagery of arid regions hasthe obvious advantage of little interference
between surface and sensor, investigatorshave shown that much geological information can be derived from imagery where theground is obscured by vegetation.
GEOLOGIC MAPPI G
The LANDSAT overview and coveragecycle makes map correction and verification anatural application to geology. InvestigatorsH. Blodget and A. Anderson of NASA's Goddard Space Flight Center constructed athree-image mosaic of southern Moroccofrom which they were able to verify and modify previously mapped lithologic boundaries,and investigate relationships between structural character and mineral emplacementfrom a regional perspective. A common procedure among LANDSAT investigators hasbeen to use the imagery as base maps uponwhich geologic interpretations of structure,lithology, and lineament patterns aresuperimposed. Another team of investigators, M. Abdel-Gawad and J. Silversteinof Rockwell International, discovered thatLANDSAT images of Baja and the Gulf ofCalifornia showed several small islands tohave been misplaced on conventional maps,both in geographic location and in topographic detail.
LANDSAT DATA: A NEW PERSPECTIVE FOR GEOLOGY 1235
M. Viljoen ofSouth Africa used LANDSATimagery to unravel the geologic relationshipsof the South African shield. This investigatorwas able to distinguish between the granitegneiss craton, adjacent metomorphic mobilebelts, and major "greenstone" intrusions.The nature of these intrusions and theircharacteristic relationship to the overallgeologic setting was recognized by Viljoen tobe similar to that found in metallic mineralmining districts in Canada (e.g., Sudbury,Ontario) and Western Australia, and suggeststhat the South African regions might containuseful concentrations of minerals as well. Inthis example, the roughly 34,OOO-squarekilometer region surveyed in a singleLANDSAT frame could be broken down intomineralization potential maps with considerable savings in time and cost to mineralexploration interests. On a larger scale,perhaps the most impressive display ofLANDSAT's map~making capability can beseen in the mosaic of the 48 conterminousUnited States, produced by the Soil Conservation Service of the U. S. Department ofAgriculture, and available to the public (Figure2).
MINERAL AND PETROLEUM EXPLORATION
The majority of LANDSAT geology investigations fall into this category primarily because of the direct impact on current and projected national needs. Mineral exploration
from LANDSAT has been accomplishedusing the following well-known geologicprinciples:
• Mineralizing fluids from within the Earthmay follow the paths of least resistance tothe surface; these paths are zones of weakness through the Earth's crust and occurwhere the solid rock has been fractured andfaulted. Thus, a concentration of "lineaments", many of which can be discerned inLANDSAT imagery, may well indicatewhere the crust is weakest and, therefore,most likely to be mineralized.
• Some rock types discernible from orbitalaltitudes are characteristically associatedwith certain types of minerals because theyindicate similar formative conditions or alteration through time.
• Mineralization may alter surface tones bysecondary enrichment, vegetation stressandJor chemical changes in the vicinity ofthe ore body, all of which can indicate thatsignificant mineral concentration has takenplace.
Using these and other, more subtle clues,geologists using LANDSAT imagery havereported varying degrees of success in minerai and petroleum exploration studies. Someof these investigators have relatedLANDSAT-discovered Iineaments to knownmineral concentrations; many of thesestudies have been undertaken in the arid regions of Western North America. E. Lathramand other geologists of the U. S. GeologicalSurvey discovered a series of intersecting re-
FIG. 2. Mosaic of continental United States compiled from LANDSAT imagery by USDA.
1236 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975
gional lineaments in a rare cloud-free NIMBUS image ofAlaska. These lineaments wereverified in LANDSAT imagery and enabledthe investigators to propose a radically different picture of mineral emplacement inAlaska. Earlier speculation suggested thatmineral deposits in Alaska were related tofold belts of the Canadian Cordillera. Basedon the occurrence of the newly discoveredregional fractures, Lathram and his coworkers suggested that mineral emplacementmight also have occurred at their intersections. The result is an alternate hypothesis formineral emplacement in Alaska, certain tostimulate interest in renewed exploration efforts in areas formerly dismissed as nonproductive (Figure 3).
Further to the south, California investigators E. Rich (1973), Abdel-Gawad, andSilverstein (1973) correlated mininglocalities with lineaments observed inLANDSAT imagery. Abdel-Gawad and Silverstein, in particular, correlated mercurymining localities with a newly discovered setof transverse faults in the Coast Ranges. Thealtered serpentine host rock and geologic setting of the mercury ore were non-definitive
EXPLANATION_Ni,Cr,FeCIIJ Cu, Mo, massive sulfides= "9. Sb.W- Mojor foult with surface
expression
EXPLANATION=Hg. Sb. W_Ni,Cr.FemJ Cu, Mo, mossi...e sulfide...... Crustal fractures- Mojor foult with surface expression
FIG. 3. Projected distribution of selected minerals in Alaska (after Lathram et aI., 1973). A.Theory ofassociaton with geosynclinal evolutionof western Cordillera. B. Theory of associationwith crustal fractures as observed in satellite imagery.
and of little value as ore guides. With therelationship demonstrated by these investigators, future exploration efforts should besimplified markedly (Figure 4). AnotherCalifornian, 1. Bechtold, demonstrated asimilar correlation between tensional fissures in the Lake Mead area (resulting fromeast-west crustal extension) and concentrations of gold, silver and other metallic oredeposits.
An interesting multilevel geochemical exploration approach was reported by M. Jensen, ofthe University ofUtah, who correlatedLANDSAT lineaments with positive aeromagnetic anomalies, and field-checked areaswhere they coincided. Soil samples wereanalyzed for mercury vapor, and those areasof highest mercury vapor concentration identified for intensive exploration.
Other investigators have attempted to correlate mineral deposits with characteristicsurface tones extracted from LANDSAT imagery visually or by computer enhancementtechniques. R. Vincent identified highly oxidized terrain overlying iron ore deposits inthe Atlantic City mining district of Wyomingby computer ratioing reflectance values ofselected pairs of ERTS bands. The resultswere analog ratio images, corrected forgeometric and atmospheric effects, whichshowed the oxidation "halos" over the ironore deposits. A. Goetz and others at JPL developed computer techniques for rock identification and structural analysis in the Colorado Plateau, eventually resulting in thediscovery of perched aquifers, ground watersources badly needed by ranchers on theCoconino Plateau of southern Arizona.
LANDSAT data have found application inpetroleum exploration as well. Two investigations have met with initial success in thisarea. E. Lathram in another phase of thestudy mentioned earlier discovered an unusual regional orientation in a series oflakeson the Alaskan Arctic Coastal Plain. Thelakes, generally oval in outline, paralleledregional lineations and deviations in the localgravity and magnetic fields. Supportingground truth coupled with LANDSAT dataled the investigators to postulate the existence of"dip" reversals and regional arching:factors which might indicate potential petroleum accumulation (Figure 5). Similargeologic trends continue to the northeast,and have aroused the interest of the petroleum industry.
Another investigation, headed by R. Collins of Eason Oil Company (Oklahoma City),correlated "hazy" surface tones discoveredin LANDSAT imagery of the Anadarko Basin
N )4"
LEGEND
~ ... Fault with evidenceof recent movement
KNOW FAULTSFAULTS INFERRED FRO.... ERTSDRAINAGE LINE
.....ERCUR" ltliNG DiSTRICT• MERCURY INES
Abde I·Gawad & Si I verste i n 1973
EARTHQUAKE EP IeENTERSL!l- ~RGNI TUDE UNKNOWN'-~AGNITUDE O. - 4.0x-~AGNtTUDE 4.1 - 4.9O-MAGNITUDE 5.0 - 5.4x- MAGN I TUDE 5.6 - 6·8.-~RGNITUDE 6.0 - 6.9K-~AGNITUDE 1.0 - 7,9.-~AONIrUDE ~·o - ~.4
N )5"
t"">ZoVl
~o>..,?>Zt'l~'"0t'l::0Vl'"0t'l(")..,:<t'l"r1o::0(')t'lot""o(')-<
FIG. 4. LANDSAT imagery of southern California and a plot of faults (after Abdel-Gawad and Silverstein, 1973),
""""1'0W-1
1238 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975
FIG. 5. Lake orientation and associatedgeophysical lineations on the Alaskan arcticcoastal plain (after Lathram et aI., 1973).
(NE Texas and SW Oklahoma) with knownproducing oil fields. Correlation exceeded 85per cent, and led the investigators tohypothesize that these surface anomalieswere the result of volatile components of thepetroleum reservoirs migrating to the surface. Whether this phenomenon is a consequence of well drilling or is a natural occurrence remains to be proven.
EARTH HAZARDS: MONITORING AND SURVEYS
Geologic hazards present a direct threat tosociety in several familiar ways. The catastrophic result of earthquakes and volcaniceruptions, and the less spectacular butequally devastating effects of erosion andflooding can be monitored and better understood through the synoptic and repetitiveoverview provided by LANDSAT 1 and 2.
LANDSAT investigators have successfullyused orbital imagery to inventory, monitor,and even forewarn of potential geologiccatastrophes. Among these are USGSgeologists Eaton and Ward, who usedLANDSAT to relay information from a seriesof data collection platforms emplaced on active, potentially eruptive volcanoes in Alaskaand Central America. DCP instrumentationconsisted of seismic event counters and borehole tiltmeters, both designed to relay datacharacteristic of the pre-eruptive phase of thevolcano. The investigation proved successfulwhen the volcano F'uego, in Guatemala,erupted with devastating force shortly afterinformation relayed from the DCP indicatedit would.
o 25 MILESJI--~I---11o 25 KILOMETERS
1004-21395
Other Earth hazards include the potential of earthquakes in many parts of theworld. LANDSAT facilities for locating regionallineaments have been used by investigators dealing with these hazards. M.Abdel-Gawad discovered evidence of recentmovement along faults in southern Californialong considered to be inactiveJ Seismichazards maps can be modified by inputs ofthis type provided by LANDSAT sensors.
L. Gedney of the University of Alaska'sGeophysical Institute constructed a mosaicof central Alaska using six LANDSAT images, clearly revealing the presence of sets of"lineaments" (faults and fractures) whichcorrelated well with the distribution of shallow focus earthquake epicenters in the region. Through these studies, an active leg ofthe Denali fault was found to lie close to abridge site over the Yukon River, and theproposed route of the Alaskan oil pipeline.Updated seismic data coupled with LANDSAT imagery will enable planners to modifytheir route selections as necessary.
Perhaps less catastrophic but equally devastating in the long term is the problem ofsoil erosion. Morrison ofthe U. S. GeologicalSurvey dealt with regions of accelerated erosion in southern Arizona. Present erosiondamage was monitored by LANDSAT, flooding and floodwater recession observed, andan erosion-susceptibility map constructed asan aid to future development.
LANDSAT programs have made significant contributions to many subspecialitieswithin geology. Some of these contributionshave already been felt in terms of correctedmaps and a more accurate awareness of prevailing seismic hazards.
Some will be felt in the future, where thepromise of undiscovered mineral and petroleum deposits can be fulfilled throughcomputer enhancement of LANDSAT datacombined with visual interpretation andsupporting ground truth.
Data collected by LANDSAT's sensors canprovide a wealth of information useful forsolving the problems facing man as he tries tolive in harmony with his environment. Onlythoughtful interpretation of the data, supplemented by the technology of moderncomputers, will enable him to maximize thebenefits "for all mankind."
REFERENCES
Abdel-Gawad, M., and J. Silverstein, 1973, "ERTSApplications in Earthquake Research andMineral Exploration in California,"Symposium on Significant Results Obtainedfrom the Earth Resources Technology
LANDSAT DATA: A NEW PERSPECTIVE FOR GEOLOGY 1239
Satellite-l, Vol. I Technical Presentations p.433-450
Bechtold, 1., M. Liggett, and J. Childs, 1973, "Regional Tectonic Control ofTertiary Mineralization, and Recent Faulting in the SouthernBasin and Range Province, an Application ofERTS-I Data," Symposium on Significant Results Obtained from the Earth ResourcesTechnology Satellite-l, Vol. I, Technical Presentations p. 425-432
Blodget, H. W., and A. T. Anderson, 1973, "AComparison ofGemini and ERTS imagery obtained over Southern Morocco," Symposiumon Significant Results Obtained from theEarth Resources Technology Satellite-l, Vol.I Technical Presentations p. 265-272
Collins, R. J., McCown, F. P., Stonis, L. P., andPetzel, G., 1973, "An evaluation of the suitability of ERTS data for the purposes of petroleum exploration", presentation G-17, ThirdERTS Symposium, December 10-14, 1973
Gedney, L. D., and J. D. Van Wormer, 1973,"Some aspects ofactive tectonism in Alaska asseen on ERTS-I imagery," Symposium onSignificant Results Obtained from Earth Resources Technology Satellite-l, Vol. I, Technical Presentation p. 451-458
Goetz, A. F. H., F. Billingsley, D. Elston, 1. Lucchitta, and E. Shoemaker, 1973, "Preliminarygeologic investigations in the ColoradoPlateau using enhanced ERTS images,"Symposium on Significant Results Obtainedfrom the Earth Resources TechnologySatellite-l, Vol. I, Technical Presentation p.403-411
Gold, D. P., R Parizek, and S. Alexander, 1973,"Analysis and Application ofERTS-1 Data forRegional Geological Mapping," Symposiumon Significant Results Obtained from theEarth Resources Technology Satellite-l, Vol.I Technical Presentations p. 231-246
Houston, R S., R Marrs, R. Breckenridge, and D.Blackstone, Jr., 1973, "Application of theERTS System to the Study of Wyoming Resources with Emphasis on the use of BasicData Products," Symposium on SignificantResults Obtained from the Earth ResourcesTechnology Satellite-l, Vol. I Technical Presentations p. 595-620
Isachsen, Y., R Fakundiny, and S. Forster, 1973,"Evaluation of ERTS-I Imagery for Geological sensing over the Diverse Geological Ter-
rains of New York State," Symposium on Significant Results Obtained from the Earth Resources Technology Satellite-l, Vol. I, Technical Presentations p. 223-230
Jensen, M., 1973, "Geology of Utah and Nevada byERTS-I Imagery," Symposium on SignificantResults Obtained from the Earth ResourcesTechnology Satellite-l Vol. I, Technical Presentations p. 247-256
Lathram, E., Tailleur, I., Patton, W. W., andFischer, W. A., 1973, "Preliminary GeologicApplication of ERTS-I Imagery in Alaska",Symposium on Significant Results Obtainedfrom the Earth Resources Technology Satellite 1, Vol. I, NASNGoddard Space FlightCenter, Greenbelt, Md. p. 257-262
Morrison, R B., and M. E. Cooley, 1973, "Application of ERTS-I Multispectral Imagery toMonitoring the Present Episode of Accelerated Erosion in Southern Arizona,"Symposium on Significant Results Obtainedfrom the Earth Resources TechnologySatellite-l, Vol. I, Technical Presentation p.283-290
Rich, E. 1., 1973, "Relation of ERTS-I detectedgeologic structure to know economic ore deposits", Symposium on Significant ResultsObtained from the Earth Resources Technology Satellite-l, Vol. I, NASNGoddard SpaceFlight Center, Greenbelt, Maryland, p.395-402
Viljoen, R., 1973, "ERTS-I Imagery as an aid to theunderstanding of the Regional Setting of BaseMetal Deposits in the North West Cape Province, South Africa," Symposium on Significant Results Obtainedfrom the Earth ResourcesTechnology Satellite-l, Vol. I, Technical Presentations p. 797-806
Vincent, R, 1973, "Ratio Maps of Iron Ore Deposits, Atlantic City District, Wyoming,"Symposium on Significant Results Obtainedfrom the Earth Resources TechnologySatellite-l, Vol. I, Technical Presentations p.379-386
Ward, P., J. Eaton, E. Endo, D. Harlow, D. Marquez, and R. Allen, 1973, "Establishment,Test and Evaluation of a Prototype VolcanoSurveillance System," Symposium on Significant Results Obtained from the Earth Resources Technology Satellite-l, Vol. I, Technical Presentations p. 305-315
Notice
The listing of the Officers of Committees of the Society in the July 1975 Yearbook issue(Page 833) showed A. Trachsel as Chairman of the Publications Committee, whereas L. W.Swanson is, in fact, the Chairman of the Publications Committee.